Device for controlling an aerodynamic surface for balancing a helicopter in terms of pitch

Abstract

A device for controlling an aerodynamic surface (E) for balancing in terms of pitch a helicopter (He) including a main rotor (R1), the fore-and-aft cyclic pitch of which is controllable by a pitch-control channel (3A) as a function of a pitch control command. According to the invention, the device includes a unit (1A) associated with the control channel (3A) for controlling the aerodynamic surface (E) in such a way that it generates lift that represents part of a command dependent on the pitch-control command, which part can be executed by the aerodynamic surface (E), and the combined pitching action of the aerodynamic surface (E) and of the main rotor (R1) represents the pitch-control command.

What is claimed is: 
     
       1. A device for controlling an aerodynamic surface for balancing a helicopter in terms of pitch, said aerodynamic surface being controllable in terms of orientation and generating lift for creating a pitching action, and said helicopter comprising a main lift and propulsion rotor, a fore-and-aft cyclic pitch of blades of said rotor being controllable by means of a pitch-control channel as a function of a command for the pitch control of the helicopter, said device comprising control means associated with said pitch-control channel, for controlling said aerodynamic surface to generate a lift which represents at least part of a first control command dependent on said pitch-control command, said part being executable by said aerodynamic surface, and wherein a combined pitching action of said aerodynamic surface and said main rotor represents said command for the pitch control of the helicopter. 
     
     
       2. A device as claimed in claim 1, wherein said first control command is determined from the difference between said pitch-control command and a reference command that represents a reference control of said main rotor.   
     
     
       3. A device as claimed in claim 2, wherein said control means are added to said pitch-control channel and control only said aerodynamic surface.   
     
     
       4. A device as claimed in claim 3, wherein said control means comprise:   a calculation unit for determining a speed control command for the aerodynamic surface from the difference between the pitch-control command and the reference command; and   means for actuating said aerodynamic surface in terms of speed as a function of the control command thus determined.   
     
     
       5. A device as claimed in claim 4, wherein the conversion of said difference which corresponds to a fore-and-aft cyclic pitch control command for the main rotor, into a value which corresponds to a control command for the aerodynamic surface is performed using a pitching moment efficiency conversion gain.   
     
     
       6. A device as claimed in claim 4, wherein said calculation unit determines said speed control command for the aerodynamic surface by performing, in succession, at least a conversion, an integration and a low-pass filtering of the difference between said pitch control command and said reference command.   
     
     
       7. A device as claimed in claim 1, wherein said control means are built into said pitch-control channel and control said aerodynamic surface and said main rotor simultaneously.   
     
     
       8. A device as claimed in claim 7, wherein said pitch-control channel comprises a linkage for transmitting the pitch-control command, and wherein said control means comprise a bell crank including two branches, said bell crank being built into said linkage and splitting the movement of the linkage between said two branches to transmit the pitch-control command,   a first of said two branches being mechanically connected to a member for actuating the aerodynamic surface and controlling the orientation thereof, and   a second of said two branches being mechanically connected to a member for actuating the main rotor, controlling the fore-and-aft cyclic pitch thereof, and wherein the mechanical connection between said second branch and said member for actuating the main rotor is elastically restrained.   
     
     
       9. A device as claimed in claim 8, wherein said mechanical connection is restrained by an elastic restraint having an adjustable neutral point which represents a reference control of said main rotor. 
     
     
       10. A device as claimed in claim 9, which further comprises means for adjusting said neutral point of said elastic restraint, as a function of characteristic parameters. 
     
     
       11. A device as claimed in claim 10, wherein said characteristic parameters are at least some of the following parameters: the temperature, the speed, the load factor, the altitude and the vertical speed of the helicopter (He).   
     
     
       12. A device as claimed in claim 8, which comprises adjustable stops limiting the movement of the mechanical connection between the first branch of the bell crank and the member for actuating the aerodynamic surface.   
     
     
       13. A device as claimed in claim 12, which comprises means for adjusting said stops as a function of characteristic parameters.   
     
     
       14. A device as claimed in claim 8, which comprises a damper connected to the mechanical connection between the first branch of the bell crank and the member for actuating the aerodynamic surface.   
     
     
       15. A device as claimed in claim 7, wherein said control means comprise a calculation unit which determines, on the one hand, a second control command transmitted to a member for actuating the aerodynamic surface, to control the orientation thereof and, on the other hand, a third control command transmitted to a member for actuating the main rotor, to control the fore-and-aft cyclic pitch thereof.   
     
     
       16. A device as claimed in claim 15, wherein said calculation unit performs a conversion between said control commands for, respectively, said aerodynamic surface and said main rotor, using a pitching moment efficiency conversion gain.   
     
     
       17. A device as claimed in claim 15, wherein said calculation unit performs low-pass filtering of said second control command.   
     
     
       18. A device as claimed in claim 15, which comprises means for measuring the angle through which the aerodynamic surface is turned, the angle thus measured being transmitted to said calculation unit to determine said third control command.   
     
     
       19. A device as claimed in claim 15, wherein said calculation unit determines said third control command from said second control command.   
     
     
       20. A device as claimed in claim 1, which comprises a calculation means for calculating said reference command as a function of the characteristic parameters.   
     
     
       21. A helicopter, which comprises the device specified in claim 1.